Web sites commonly include content from external sources. Most commonly, an HTML file for a website may contain hyperlinks that correspond to contents provided by a third party. Content that is included from external sources can cause a number of problems since the publisher of the host website does not have control over the external content. For example, the external content may no longer exist, may be temporarily unavailable, may have changed over time, or may contain computer software such as scripts that disrupts the host application.
In one scenario, embedded web pages attempt to disrupt a host application by frame breaking or through other scripting techniques. A web publisher that controls or owns a website does not have control over the content in the embedded web pages. As such, these embedded web pages may perform frame breaking to the unsuspecting web publisher by hijacking the host application. The frame breaking may cause the host application to terminate or redirect to another web page unintended by the user.
In a second scenario, third-party content that was previously discovered and placed in the publisher's website either directly or through a hyperlink may now be inaccessible, unavailable, or different from the previous version. Typically, the host application cannot render inaccessible or unavailable third-party content, but can render different third-party content. The second scenario is indicative of a changed URL or a changed third-party content of a URL.